Apparatus for the production of music



Jan. 27, 1942. B. F. MlEssNER 2,271,460

APPARATUS FOR THE PRODUCTION OF MUSIC med oct. 2z, 1940 2 sheets-sheet 11 maentor Jamin E'Hfrsner Jan. 27, 1942- B. F. MlEssNER APPARATUS FORTHE PRODUCTION 0F MUSIC Cltorneg Patented Jan. 27, 1942 2,271,460APPARATUS FOB THE PMDUCTIUN F MUSIC Harding Township, Morris or toMiessner Inventions, Township, Morris County, N. J.,

a corporation of New Jersey Application October 22, 1940, Serial No.362,192 19 Claims. (Cl. 84-236) This invention relates to musicalinstruments, and more ventina contemplates especially, though not in allaspects limitatively, instruments of the piano type. wherein timedStrings or other vibrators are percussively. excited by hammers underthe control of a. keyboard. Ihe description will accordingly be prentedlargely with relation to 'a Iliana The apparatus for eiecting theexcitation of been positively propelled before contact. Concomitantlyintroduced with the eseiiective in conjunction with apparatus speciallyintroduced for the performance of the third of the abovementionedfunctions.

The later-introduced constructions to perform the third function havebeen arrangements to delay the fall of the hammer from its checked toitsdormant position, so that the jack 0f the escapesuch as the so-calledand would completely ment mechanism could restore itself to operativeposition under the hammer before complete key release. Typically theyhave comprised a socalled "repetition lever" incorporated, in theactions for grand (horizontal-string) pianos, in a complicated assemblyinvolving adjustable tensloning and movement-limiting devices; or,somewhat less satisiactorily in the action for upright (vertical-string)planos. a particular arrangement and balancing of parts to suppresstendencies of the hammer to return to dormant position, together withspecial adjustably arranged means bridle-tape to enforce that return inthe last portion of key release.

All these arrangements reached essentially their present stage ofdevelopment approximately a. hundred years ago; and ever since then thepiano action has resisted allattempts at obtaining a proper perfomanceof its functions with any appreciable simplication of its construction.Unable to reduce a complexity which is actually almost appalling, theindustry has simply become inured to it, and has contented itself withthe mere improvement of the components of the action. methods for itsmanufacture, and the like.

I`have observed that the complexity of the action is actuallyattributable almost entirely to the escapement mechanism. It is quitetrue that this mechanism itself constitutes only a minor part of thecomplexity. But its presence is the immediate occasion of the need forthe back-check. and for the entire construction resorted to forperforming the third function abovementlonedfor that function would beinherently performed, disappear as one requiring special constructions,if there were no escapement.

I have further discovered that it is possible to entirely satisfactorilyperform the second function abovementioned without an escapementmechanism. Prior attempts to do this have failed be.

cause of the extreme nature of the requirements. It must be recalledthat the hammer must not be tripped (which term I construe and use inits broad sense, as meaning simply released or freed from the propellingforce of the key) until very close to the string, for otherwise the useo1' a relatively slow key depression-necessary for a full range of touchcontrol-will not serve to cause the striking of the string. On the otherhand unless, upon tripping, the propelling means is gotten out of theway of the hammer, the rebound of the hammer from the string to thatnowverynearby propelling means has occasioned an unwanted bounce of thehammer back to the string,l or series of such bounces, in either eventtion of relatively Y tie-member Il appearing in Figure I have stillfurther discovered that, in an action from which the escapementmechanism is eliminated in a manner not compromising the features ofperformance above noted as requisites the certainty and speed with whichrepetibe indulged in is not only unavailable the complete omission ofthe complicated mechanism specially included in the latter for theexpress purpose of facilitating repetition, that is, for the thirdfunction abovementioned.

Accordingly it is a general object of my invention to simplify theconventional action. And it is an object to effect this simplificationwithout impairing the assurance of vibrator excitation with relativelyslow key velocities, or the assurance of absence of bouncing of thehammer back to the vibrator after its initial rebound therefrom, or theperfection of the available repetition.

It is another object to improve the certainty and speed with which therepetition of a note may be indulged in. And it is an object to do thiswhile greatly simplifying the action.

It is another object to provide a satisfactory action without anescapement mechanism. And it is an object to provide such an actionwhich jointly assures vibrator excitation with relatively slow keyvelocities, assures absence of undesired plural contactings of vibratorby hammer, and renders available excellent repetition.

It is another object to provide such improved actions especially adaptedfor the excitation of relatively small and light vibrators, such as aresound.

proved actions especially adapted for the excitalight strings held underrelatively low longitudinal tension.

It is an object to provide a generally simplified and improved pianoaction. l

It is an object to provide an improved and simplified construction for apiano, and in particular for an electronic piano.

Other and allied objects will more fully appear from the followingdescription d the appended claims.

In the description reference is had to the accompanying drawings, ofwhich:

Figure l is a cross-sectional view taken in a vertical front-and-backextending plane through the forward portion of a horizontal-string pianoin which ,my invention has been incorporated in one form:

Figure 2 is a similar view taken through the rear portion of the sameinstrument, this figure also including a schematic illustration of themechanica-electro-acoustic translating system which may be employed inthis instrument;

Figure 2a is an enlarged elevational view of the Figure 3 is a verticalcross-sectional view taken substantially along the line 3-3 of Figure 1;

Figure 411s an enlargement of a small portionFlgureisaviewgenerallysixnilartosure 4 but illustrating the t of myinvention in a modified form;

Fig1n'e6isaviewgenerallysimilartomgure4 but illustrating the embodimentof my invention in another modified form;

Flgureaisaview generallysimilartorlgure 4 but illustrating theembodiment o! my invention in still another modied form:

Figure? isa cross-sectionalviewtakenina embodiment of my invention in amable steel beams welded together. comprises a transverse front beam iopen toward the front; a also of U-shape and open towar a plurality offront-and-back T-heams! terminally weldedtothe e 1' "afbeams. At thefront (as seen in Figure l) the vertical part of each T-beam may bebatted against and welded to the reato! thebeam I. and the horizontalpart of each T-beam mar be extended underneath and welded to the bottomof thebeam l. Attherear (asseeninsure) the vertical part of each T-beammay be batted against and welded to the upper and lower front edges ofthe beam I, the horizontal part of each T-heam being extended underneathand welded tothebottomof thebeaml. The beams may be suitably inclined ortapered toward each other at the (treble) extremity of the instrument toprovide the diminishinzstrnslength: thistaperinsisindicatedin thedrawings, for example by the fractional showings I'andloftheupperportionsofi and 2. The rear is and held within the thefront of the mest-plank. whose topmaybeatalowerleveithanthtofthereerportiommayatendforwardlytoholdnminspms l.

rearbeamt thefronkand inverted be moet effectiveagainsttheeifectoftheatringtension.

Attherearoftheframqasseinguxel there may be provided a bridge structure.erablythisisofthecanilevertypedisclosedand claimed in my cri-pendingapplication Serial No.

229,650, tiled September 13, 1938 (on which Patent No. 2,225,195 hassince been issued). It may comprise a plate 8 whose rear portion isclamped, through strips 3 and screws I0, to the inside bottom surface ofthe top part of rear beam 2, and extending therefrom to projectforwardly beyond that beam. n the bottom of a forward portion of theplate is secured a string bridge I2. As pointed out in the co-pendingapplication last abovementioned, the front-and-back dimension of theclamping strips B may be progressively varied transversely of theinstrument, to result in a progressively varying overhang of the bridgefrom the clamped part of plate B, with resulting progressive variationof the compliance of the l bridge support to up-and-down vibration. Se-

cured to the bottom of plate 8 forward of the string bridge I2, and ifdesired integral therewith, may be a further or pick-up bridge I3 ofless vertical dimension than the string bridge, the function of `thebridge I3v being hereinafter referred to.

It may be pointed out that for the purpose of accommodation to thepresence of the T-beams 3, the plate 8 and the bridges I2 and I3 may beformed in sections separated from each other sulliciently to pass freelythe T-beams 3. Preferably, however, these separate sections will becoupled to each other around each T-beam 3, for the transmission ofvibrations transversely of the instrument (or longitudinally of thebridge) as though the elements under discussion had'not beensectionalized. This may be done for example by securing, to theextremities of the sections of bridge I3 on each side of a T- beam 3,the respective extreme portions of an inverted U-shaped tie-member Ilstraddling the T-beam, as best seen in the enlarged Figure 2a.

Each string 1 may pass across and bear up against the bottom surface ofthe string bridge I2, being held thereto by engagement with two pins Il.From the rear pins II rearwardly, and from the front pins II forwardly,the bridge surface may be bevelled, so that the terminal string contactsare right at the pins. Each front pin I I of course defines the rear endof the active portion of its respective string. From its rear pinrearwardly each string may pass, inclinedly'upwardly at an anglesuitable for theY appropriate bearing on the bridge I2, to a doublycountersunk hole 2a in the vertical rear portion of beam 2, and afterpassing therethrough may have its extremity anchored to a pin I5therebelow.

The particular instrument chosen for illustrative purposes and shown inFigures 1 through 4 is intended to produce its tones through the mediumof mechanica-electro-acoustic translation of the vibrations of itsstrings, the attendant non-necessity for a soundboard permitting theemployment of the simplified cantilever vibratile bridge support alreadydescribed. Typical means for translating electric oscillations from thestrings may include a set of pick-up electrodes IB, preferably in theform of inverted screws adjustably threaded through the pick-up bridgeI3 and plate (which preferably are formed of insulating material such asBakelite"). The heads of the electrode screws I6 may be in spacedrelation to the respective strings 1, while their upper extremitiesmaybe slotted for easy screwdriver adjustment of the spaced relation. Inthe interest of simplicity Figures l and 2 have illustrated only onestring 1 and its pick-up electrode I6; but it will be understood thatatleast one of each per note will be employed, as indicated for examplein Figure 2a. Further as indicated in Figure 2a, some convenient meansmay be employed for electrically interconnecting the several electrodes,such as the conductor or soft copper wire I1 wrapped or threaded fromone to another in succession above the plate 3.

A typical completion o! the translating apparatus along well-known lineshas been schematically illustrated in Figure 2. Between the pickupelectrodes I6 on the one hand and the striDSS of the instrument on theother there may be electrically connected in series a source 2l ofelectrical energy and a resistance 2| (connection to the strings beingconveniently through the medium of the rear beam 2). If the source lllbe operated as a high-voltage D. C. source, it serves to charge thecapacity between strings 1 and the pick-up electrodes IB and, because ofresistance 2|, oscillatory variations in that capacity caused by stringvibration will cause a corresponding oscillatory variation in thevoltage across the capacity. If the source 2I| be operated as asuperaudible-frequency A. C. source, it serves to send through thestrings-to-electrodescapacity a current whose amplitude, again in viewof resistance 2|, will be modulated or oscillatorily varied at thestring. vibrational frequencies. In either event the oscillatorycomponents in the voltage across the strings-to-electrodes capacity maybe transferred, as through a coupling condenser 22, to the input of anamplifier 23 (which, in the case of the A. C. operation of source 20.will also be operated as a demodulator). Theroutput of the amplifier 23,comprisingamplied electric oscil lations representing the vibrations ofthe strings 1, may be subjected to any or all forms of control known inthe art, non-limitatively including control of amplitude as bypotentiometer 24 operated by pedal 25, and may be further amplified andtranslated into sound by amplifier 26 and loudspeaker 21, respectively.

Resistance 2I and condenser 22, and the leads and terminals connectedthereto, may be suitably electrostatically shielded, as schematicallyindicated by shielding 28 in Figure 2. Shielding of the electrodesA Ii,which is usually suflciently provided inherently by the strings insofaras ther under-side of the electrodes is concerned, may be carried outabove the electrodes by a conductive plate or member 2! hinged to thetop of beam 2 and extending to overhang the electrodes; this member hasbeen illustrated in partially raised position in Figure 2.

The frame or plate constituted by beams I, 2 and 3, and thus thewrest-plank, bridges, strings, pick-up electrodes, etc., is held in thecase of the instrument in some known manner not necessary herein toshow, though preferably according to the vibration-insulation teachingsof Patent No. 1,912,293 to me. Forming a part of the case of theinstrument is the key-bed 3|. seen in Figure 1. When the front finishingrail BI is removed from the key-bed, the removable part of the actionmay be slid from the front into its place on the key-bed. In the form ofmy'invention illustrated in these gures, this removable action portionincludes the usual framework 'formed by front, center and rear rails 32,33 and 3l respectively, held in proper mutual relationship byfront-and-back extending strips 35. The keys 36 are pivoted on thecenter rail 33 in the usual manner, and may be provided with .the usualguiding arrangements at the front, including guide pins 36a extendingupwardly from front rail 32 and felt washers 36h surrounding the pins.In the illustrated form oi the invention the rearward extension of thekeys proper is stopped short of the rear rail 34; but to the rear bottomsurfaces of the keys are secured respective bars or members' 31 ofrectangular cross-section, these extending rearwardly to overhang therear rail 34 and normally to rest thereon through the felt or like strip38. The bars 31 may for example be oi metal, and may serve to properlyweight the key-as well as to constitute an active rear portion at aspace-savingly small elevation above the key-bed.

When in position in the instrument the rear rail 34 of the removableaction portion may abut (through a veryl thin felt strip 38 if desired)against a transverse vertical block 60 secured to the top of the key bed30. To the top of the block 60 is secured a forwardly overhangingtransverse horizontal block 6I. To the bottom of the latter block may besecured a felt strip E! which may form an up-stop for the etl'ectiverear portion of each key (i. e., for the bar l1), the washers 36h whichform the usual front down-stops for the keys being adjusted to check thekey motion coincidentally with the felt strip S2. The provision of B2 aswell as Sib is desirable in order that the key motion in the vicinity ofthe hammer shall be stopped at a discrete point, without theaccuracy-impairing iniluence oi' the bowing or whipping which mightotherwise take piace throughout the key length, and the like.

Attention may now be directed to the mecha.- nism interposed betweeneach bar 31 (which has been seen to constitute the active rear portionof the key) and the respective string-this constituting a typicalembodiment of the great sim pliiication of the action according to myinvention. In its most basic aspect the invention is not limited as tothe form of the hammer or as to its mode of movement relative to thekey. I have found, however, that a very light cylindrically shapedhammer, vprovided with an appropriate head and moved simply in an axialdirection toward and away from the string, is admirably adapted to theexcitation of the relatively light, low-tension strings which arepreferably employed in an electronic piano of the disclosedconstruction, and such hammers 'have been illustrated as 46 in Figure 1and in the enlarged fractional Figure 4.

Each hammer may comprise a cylindrical side wail 41; a button or plug 4lclosing its bottom extremity; and a button or plug 49 closingl its topextremity-the button 49 preferably having s top surface which is convex,and whose diameter is greater than that of the hammer side wall 41 sothat a shoulder is formed therewith. These elements may be formed of anysuitable though preferably light material-for example, ci aluminum oraluminum-alloy, or of plastic materail such as 'Bakelite'L-and may becemented or otherwise firmly secured together. If desired there may besubstituted, as a material for the top button 49, a material appropriateto the striking of the string, such for example as leather or hard felt,in which case the button will form the head of the hammer. I havepreferred, however, and have illustrated, a covering 49d over the button49, the button and covering then together constituting the hammer head,in which casethe special material need not be employed for 9.

The hammers may be retained for vertical axial movement in respectivefelt-hushed holes d! in a rail 43 extending transversely across theinstrument, the heads of the hammers normally resting on a thin feltstrip 45 secured on top of the rail. The desirable normal spacing ofhammer-head from string (typically of the order of may require that thetop portion of the rail 43 be cut away to admit the lower portions ofthe T-beams 3 (to the bottoms of which the rail 43 may be secured). Therail may be effectively restored to normal top level on each side oi thevertical part oi the T-beams by small blocks 44, secured on top of thehorizontal portions of those beams, as seen in Figure 3. Bushed holesfalling within the width of those horizontal portions are of courseextended therethrough and through the blocks 44 thereabove.

Each hammer terminates at a distance above a respective one of thekey-extensions or bars 31. Each key is arranged upon depression (of itsforward extremity) to impart a rising movement to the hammer, and thisis simply done by providing on each bar 31 below the respective hammer acapstan or hex-headed screw 40 threaded downwardly into the bar. Thevertical position of the head of screw 40 is of course adjustable byrotation of the screw. While the primary purpose of this adjustabilityis a function hereinafter made apparent, it may here be noted that theproportioning of the parts is such that there will normally be a slightclearance between the top of the screw 40 and the bottom of the hammer,permitting theiree removal and insertion of the removable actionportion.

Ordinarily the mechanism interposed between key and string comprises notonly the hammer but also the escapement, checking and repetitionmechanisms. For al1 these latter I substitute a bounce-suppressingmeans, which I have found it possible to construct in so eiective a formthat the energy of the hammer, rebounding from the string, will beattenuated to the extreme degree necessary to preclude bouncing of thehammer back to the string-even though the distance through which therebound occurs, and through which a bounce would bring the hammer backinto the repeated contact with the string, be only a tiny traction ofthe total original hammer stroke. Such a result has hitherto beenthought quite incapable oi achievement; and so it is, ii there be reliedon simply the absorption of hammer energy occurring in a pad or the likeagainst which the hammer rebounds and which is made of one of the felt,leather or like materials which in piano construction are alwaysresorted to for the performance oi' shock-insulating and similarfunctions. (Such materials are in their general nature iibrous; theirlargely inter-secured iibres, following deformation of the material,tend to restore themselves to original arrangement with very littlework; and their reactions to defamation are therefore essentiallyresilient rather than energy-absorptive.)

I have found that. satisfactory bounce-suppressing means may beconstructed according to either of two principles. though I prefer onein which both principles are aptly combined. One principle is that ofenergy oppositionby a mass moved at appropriate times into opposingimpact against the mass of the hammer (or, when this mass is a part ofthe hammer, into opposing impact against the residual mass of thehammer). The other principle is that oi energy absorption-but with amaterial o! an entirely dinerent Aorder oi' effectiveness from thoseabovementioned.

I may here note that the type o! energy-absorptive material which I havefound to have the entirely different order oi eiiectiveness is one whosedeformation and restoration involves much work; it may '.'generally bedescribed as an effectively uid mass characterized by a high viscosity.I use the*V term mass" rather than substance" to indicate that thefluidity represents a relative movement oi particles oi the material,whether those particles be the molecules oi' a truly fluid or semi-uidsubstance, or individual larger particles oi a solid substance whichtogether form an agglomerate mass. I use the term viscosity in itsaccepted sense as to ilulds and semi-fluids, and in its obviouslyequivalent sense as to an agglomerato. By way of examples oi such a massof essentially uid or semiiiuid substance may be'mentioned masses oftar, Viscoloid, gum (for example in such form as candy gum drops),jelly, putty, plasticized clay, oil, natural resins, synthetic resins,etc. By way oi examples ci such a mass oi' individual solid particlesmay be mentioned agglomeraties of sugar, salt, sand, iine gravel orstone, carbon granules, lead or other metallic particles, and the like.1t will of course be understood that the foregoing examples arepresented simply to show typical kinds of material ofthe general natureto which I resort, and have not been set forth with any eiort at specialarrangement in-respect of their relative viscosities--which may varyconsiderably with precise chemical compositions (as in the case of uidsor semi-iiuids). with particle size (as in the case o the agglomerates)and with other factors. It will also be understood that the best choiceoi a preferred material depends not only on available high visclty, buton ease oi handling and embodiment in the construction otherwisecontemplated, imperviousness in that construction to chemical orphysical change or deterioration with time or use, and the like.

The embodiment o! my invention illustrated in Figures l through 4utilizes jointly the two principles abovementioned. They are madeeiective therein simply by the illllng oi the hollow hammer 4B.preferably to a maior fraction 0i its height, by one of the materialsabovemenhoned-preferably one oi the agglomerates, such as ilne gravel.The special and salutary eects for which this simple structure isresponsible will become apparent from a consideration ol the operationof the action.

'As key depression is begun the screw ln will almost at once be broughtup into contact with the bottom oi the hammer It. As key depression iscontinued the hammer, its bottom now driven by screw 40, will bepropelled toward `the string. Very slightly before the hammer head l!reaches the string the key motion will be stopped by impingement o! 31on il. The momentum of the moving hammer, however, causes it to continueits movement: and since it is now tree oi connection with the key, itmay in a broad sense be said to have been tripped. Travelling the slightdistance from tripping point to string, the hammer strikes the stringand rebounds downwardly therefrom. The element which drove the hammerupwardly-the screw A D-has not been displaced laterally from its drivingpath by any escapement nor has it been retracted downwardly (unless inthe exceptional case of extreme stacatto key manipulation). It theretoreoccupies the position it had when the hammer was tripped: andaccordingly the distance o! tree rebound oi the hammer is only equal tothe small distance oi' its original movement alter trinnins.

Inthe absence of the special features of my invention, the hammer,striking the screw 40 at the conclusion oi its very short rebound, wouldbounce upwardly again through the same small distance to strike thestring a second time.V Indeed. i! the original key velocity had been atall great, the hammer might repeat the reboundbounce cycle, orstring-to-screw oscillation, several times, and thus cause a third oreven iurther strikings oi the string. But there are two eii'ects of theeiectively nuid mass ill whichy severally and iointlyvact to suppressthis bounc- During the upward movement of the hammer this mass, alreadyurged by gravity to occupy the lowest possible position within thehammer, undergoes little movement withlh itself or relative to thehammer. But when the hammer movement is stopped and reversed by itsstriking oi and rebounding from the string, the momentum oi' the masslil causes it to continue upwardly into impact against the bottom(interior) surface of the hammer head 49. In view of the effectivelyfluid nature oi the mass 49, this impact will not be entirely discrete,but will be effectively distributed over a minute time interval. Byproper choice oi' the extent to which the filling of the hammer iscarried, this impact or at least the principal 'portion thereof isreadily caused to occur during the rebound of the hammer-i. e., after ithas begun its rebound from the string but before it has come back intoimpingement against the screw 40. 'Ihis impact oi the upwardly movingmass 5U against the downwardly moving mass of the hammer oers an abruptopposition to the kinetic energy of the latter, a large percentage ofwhich is thereby dissipated in the form oi heat attendant on the impact.The hammer thus reaches the screw III with much of its kinetic energyalready dissipated by the described impact.

The first effect does not stop here, however. By the end ofthe hammerrebound the mass Sli `has come to occupy essentially the highestpossible position within the hammer, and is moving downwardly with thehammer. When the downward hammer rebound is stopped by the screw l0, themomentum of the mass B0 causes it to continue downwardly into impactagainst the top (interior) surface of the hammer bottom 48. This impactor at least the' principal portion thereof will occur well before therehas been completed any string-ward bounce oi' the hammer which tends toresult from such kinetic energy as the hammer may still have after theearlier (above described) impact-dissipation. This second impact of themass til, now moving downwardly and directed against the hammer nowtending to move upwardly, oiers an abrupt that the :continued keydepression will raise the upon key release. It will of course beunderstood that the impedance which it is' desirable to add by anarrangement of this character is at maximum of a relatively smallmagnitude. and that the constants of the springs l will be chosenappropriately to this fact.

In connection with the screw 10a, there may be noted an advantage ofemploying this as a sole means for retaining the bar 31 against thebottom of the key proper. This advantage is that the bar may then besubjected to any slight lateral adjustment (about the screw as a pivot)which may be necessary to accurately align the energy-absorbing device lwith the bottom of its respective hammer. The screw lla may for examplebe threaded through the bar l1, and after tightening the bar in anydesired adjustment may be locked by tightening a lock nut b against thebottom of the bar.

In the description of operation incorporated above there has been nospecial mention of the operation as to repetition, or upon there-depression of the key after an incomplete release thereof. But sincethe hammer bottom comes essentially instantly, after string striking,into a renewed continuous contact with the screw lil (that is,continuous subject only to the inconsequential exception of the veryslight spacing when the key is fully released), it will be apparent thatthe action is inherently adapted to perfect repetition with just asminute a degree of key release as will provide any opportunity at allfor signicant re-depression. Simply stated, the otherwise always presentproblem of providing for satisfactory repetition has been not Amerelysolved, but altogether eliminated as a problem, in connection with theelimination oi the escapement.

The instrument of Figures 1 through 4 has so far been described withoutreference to the usual string dempers, or vibration-terminators. Thesemay of course be provided, fundamentally in the customary arrangement ofnormally resting on the respective strings, being respectively raisedtherefrom by depression of the respective keys, and being all raised asa unit by depression of an appropriate pedal. I have, however.incorporated the dampers in this instrument in a particularly simplemanner, which may now be described.

The dampers may comprise suitable felt pads 1I, respectively secured tothe bottoms o! blocks 12. Inthesideofeachblockmaybesecuredthe upperextremity of a respective damper rod 13. At some distance below thebottom oi its damper pad 1l each rod 'Il may beprovided with an oil'-set 13a. to substantially align below the respective string the portionof the rod which lies below the onset. This lower portion of each rodmay pass through a respective felt-hushed hole 14 in a damper rail 1I.which may for example be conveniently formed as a rearward extension ofthe lower and middle p0rtions of hammer rail Il: when the damper restson the string the respective rod odset 13a may be slightly above the topof the rail 16. From the rail 15 the rods 13 may extend downwardly toterminate slightly spaced above respective hard felt or other durablepads 1l. which are respectively securedontopoi'theseveralbars'lbehindthe devices Il. It will be understood that the ver! nrst part of keywill bring the respective felt pad It into impingement against thebottom of the respective damper rod, and

respective damper from the' string.

To retain the dampers against rotation about their rods 13 I employ asimple arrangement which may comprise a respective pin il extendingforwardly from` each damper block 'I2 into a respective vertical slot 18cut in a transverse vertical plate 19, which by reason of the severalslots 18 therein may be likened to a comb with upwardly directed teeth.The top of the plate or comb-member 19 may be clamped between the irontand back portions of a rail B0, disposed diagonally forwardly of andabove the dempers. By this simple arrangement the dampers are retainedagainst rotation without recourse to the specifically pivoted individualdamper ilanges and attendant parts customarily employed.

A limit for the upward movements of the dampers, so that they will notappreciably overshoot their intended rise by reason of momentumdeveloped on faster key depressions, may now be asociated with thedempers themselves. This .may consist simply in a felt or like strip 82secured to the bottom of a rail BI which may be ilxedly mounted at asuitable elevation above the dampers.

To lift al] the dempers at once from the strings, a suitable pivotedpedal such as 83 acting through rod 84 may upon depression lift the rail80 and thus the plate or comb-member 19. It is to render thisplate-lifting eifectivelon the damper pins 11 that the slots 18 are notcut through to the bottom of the plate 19, but that instead the bottomportion of the plate is made transversely continuous, with the pins 11normally disposed slightly thereabove. To establish a proper path forthe limited upward movement of the rail Bil by the pedal, arms such as85 may be secured to the rail and may extend a distance rearwardlytherefrom to fixed pivots such as B6.

It will be understood that while I have specially mentioned one of theagglomerates as a typical material for the effectively iluid mass 5l inconnection with Figures l through 4. there may be substituted therefor asemi-fluid or fluid-preferably the latter, since the very restrictedspace in which it is employed in this embodiment tends to require areasonable uidlty so that the desired movements will actually occur.Figure 5 illustrates this modification, the mass ln question appearingas 6I therein, and comprising for example an oil of quite highviscosity.

While I prefer to rely on the joint action of both of the effectsdiscussed above, I may rely wholly or almost entirely on the first. oropposing-impact. one alone.` In such a case, for example, theeffectively fluid mass lill may be replaced by a discrete mass. This Ihave illustrated in Figure 6, wherein the hammer proper may again be asin earlier figures, but wherein there is provided internally thereof asolid rod I2 of length somewhat less than the internal hammer length.

lf desired, at the ends of this rod there may be provided deformablebumpers" of viscous material, so that there will be an energy-absorbingaction supplementing the opposing-impact action at least at and aboutthe instants of those impacts. A bumper I3 carried by the rod I2 isshown at the top of the latter. This may for example comprise a smallapproximately hemispherical mass lla of viscous material, preferably oneof the semi-fluids; and, to prevent any possible sticking as well as toprovide a slight but denite urge to restoration after deformation, avery thin covering 53h oi' rubber stretched over it and securing it tothe rod. A similarly active bumper 53, this one for example loose withinthe hammer below the rod 52, is shown as comprising the very thin rubbersphere 54h iilled with the mass 54a of viscous material.

A better supplement to the opposing-impact action of the discrete massor rod 52 may be provided be a means offering an energy-absorbingaction-preferably a viscous one-during all movements of the mass 52relative to the hammer proper, instead o! merely upon its impacts. Whilesuch a means may take a variety of forms, it is very convenientlyprovided by a filling of oil or the like within the hammer surroundingthe rod 52. Such a filling has been illustrated as 55 in Figure 6 inaddition to the bumpers 53-5l, though it will be understood thatordinarily one or the other, rather than both, these expedients would beemployed.

Particularly if the diameter of the mass or rod 52 be made almost asgreat as the internal diameter of the hammer proper, the oil fillingneed not be a complete one. Thus in Figure 6a I have shown the mass orrod 52' (with which no bumpers are illustrated) surrounded with only avery small quantity of oil 55' This produces a structure which I havefound especially effective.

Particularly in the constructions of these Figures 6 and 6a, it may benoted that the movement of the loosely carried mass (e. g., 52') uponhammer impacts may not always extend to produce an impact of the massagainst the hammer. This, however, does not preclude an eil'ectiveaction; for the movement of the mass which does occur deforms orinternally moves the viscous material (e. g., oil 55'), which is veryeffective to absorb the energy of the hammer.

In Figure '7 I have shown another embodiment of my invention, in a pianowhich may for example also operate electronically, but which is ofupright or vertical-string arrangement. Its general construction,illustrated for simplicity in a single figure (Figure 7) without attemptto indicate tapering of the lengths of progressive strings, may first bebrieby described. The plate or frame is again formed of suitable steelbeams welded together, but the transverse beams have been shown by wayof variation as of L-shape; these are the top beam and the bottom beam|02, the vertical portion of each beam extending upwardly and thehorizontal portion forwardly from the angle therebetween. T-beams |03may extend between the beams |0| and |02, their central cross-sectionalportions being forwardly directed and terminally butted against andwelded to the. horizontal portions of |0| and |02, and their crossportions being butted against and welded to the vertical portions of |0|and |02. The wrest-plank |03 may be disposed within the angle of beam|0|, and may hold the forwardly extending tuning pins |05; from them therespective strings |01 may pass downwardly over a ledge |0|a which maybe formed by the i'orward edge of beam |0| and which defines the upperextremity of the active string length.

The string bridge H2, whose rear portion may be extended upwardly toform a pick-up bridge I3, may be held in front of the vertical portionof the bottom beam |02 near the top of the latter. To provide forvibratility of the bridge there may be interposed between it and thebeam |02 a strip |00 of resilient material extending transversely oi theinstrument, the front and back surfaces of this strip for example beingcemented to bridge and beam respectively. If desired. as a means ofdamping the bridge vibration and hence increasing the rate of damping ofthe strings, the strip |00 may be split longitudinally and between itstwo portions there may be interposed a strip or mass |00 of one of theerrectively fluid, viscous substances abovementioned (preferably one ofthe semi-fluid materials), the front and back surfaces of this material|00 contacting the bridge and beam respectively. The strings |01 will ofcourse pass over the forward face of the bridge, engaging bridge pinsand may pass on down to terminate in respective pins I5 extendingforwardly from the front edge of beam |02. The parts will of course beapportioned to provide a proper rearward bearing of the strings againstthe bridge, so that the strings supplement any other means employed inholding the bridge in the illustrated and described position. The bridgeand associated transverse elements (e. g., |00, |09) may of course beinterrupted at the beams |03; but the bridge may be unified for thewhole instrument by tiebars Ill straddling those beams (analogous to I4of earlier figures), preferably secured to both top and bottom bridgesurfaces.

The translation of string vibrations into sound may be effected by anyappropriate translating apparatus; for example a system similar to thatoi earlier figures may be employed, and this has been schematicallyillustrated by the showing of the pick-up electrode H0.

The key bed |30, forming a part of the case of the instrument (in whichthe unit formed by the elements already described is of courseappropriately held), supports the removable part of the action. Thispart may be very generally similar to that described for earlierfigures, and has been shown as including the center and rear rails |33and |34 and the front-and-back extending strips |35 holding them inproper relationship; the keys |35 pivoted on |33; and the bars |31conveniently employed as the rarmost portions of the respective keys andnormally resting on rail |30 through felt or like strip |30.

With the vertical strings of this embodiment it is convenient to employpivoted hammers. To provide a suitable pivoting support therefor, a rail|43 may be ilxed slightly in front of the strings and above the rearextremities of the bars |31; this rail may for example be held by thetop extremities of screws or posts |62, whose bottom extremities may besecured in the key bed |30 and which may pass upwardly therefrom atsuitable intervals. The forward portion of the hammer rail mayconveniently be employed in forming a rear up-stop for the keys;accordingly a felt strip |02 may be secured to its bottom, to be inipinged on-by the rear portions of the bars |31 upon key depression.

The hammers |40 for this embodiment may be very simply formed from at,light metal strip, bent into a closed form eievationally approximating atriangle. The rear end of the base of the triangle may form the pivotingpoint: and the pivoting may be carried out by a suitable cloth strip |45folded back on itself at this point. one fold of the strip being securedto the bottom of the hammer base and the other to the top surface of thehammer rail |43. Normally. since the center of gravity of the hammerlies forwardly of the pivoting point, the top fold of the strip |05 willbe closed against the bottom fold, as uiustrated. establishing a manualposition for the hammer. From the pivoting point the rear leg of thehammer may extend upwardly for a distance, and may then be formed tohave a rearwardly directed, rounded surface or head Ilia over which maybe secured a piece III of leather or other suitable string-contactingmaterial. From the rounded surface Illia the forward leg of the hammermay extend diagonally downwardly and forwardly to join the forwardportion of the base of the hammer forwardly of the rail M3, completingthe approximate triangle; the extremities of the forward leg and thebase may be held together and bent to form a horizontallug Mib. The topsurface of the hammer rail |43 may conveniently slope downwardly to thefront, so as to bring the lug Mlle reasonably close to the top of thebar |31 when the hammer occupies its normal position. Downwardly throughthis lug llllb there may be adjustably threaded a screw IIS.

I pointed out above that for bounce suppression I might rely entirely onthe principle of energy absorption with the effectively fluid, viscousmaterials, and without the use of the opposing-impact principle whichhas been present in the embodiments through Figure 6. I have taken theembodiment of Figures 7-8 as a typical one in which to show this entirereliance.4

embodiment, nor oi' the other or broader reliance to a grand-piano oraxially-movable-hammer embodiment, or the like, for various features ofthe embodiments will obviously be interchangeable by those skilled inthe art.

In broad analogy to earlier embodiments, the energy-absorptive materialis again disposed to be deformed, or internally moved, by the hammer onits rebound from the string. Since the opposing-impact principle is notbeing relied on, however, the material is not carried by the hammer inthe special manner permitting its independent movement. Indeed, it mayif desired not be carried by the hammer at all, but rather by the keyandthe latter disposition I have chosen for showing in Figures 7-8. Mostconveniently in such a case the material will be held in some form ofretaining means, which with the material itself is convenientlydesignated as an energy-absorbing device. It will be understood,however. that the retaining means must leave the material e'ectivelyexposed to the energy of the hammer so that it will be deformed thereby.

In Figures 7-8 I have illustrated a respective and thus, broadly, theretaining means, is accordingly characterized by a slight resiliency.This resiliency is sufficient to insure the repeated return of thematerial and device to a predetermined normal or dormant condition, butis small enough sorthat the predominant reaction of the device remains aviscous or resistive reaction.

While the material may be broadly any such eHectively fluid, viscousmaterial as has been typically suggested above (fluid, semi-fluid oragglomerate) I have preferred in this construction to employ asemi-fluid such as or very similar to gum in the abovementloned form.While that itself has proven quite satisfactory, it is plobably somewhatless impervious to ultimate change than for example the syntheticresinsand to the latter I may point for a material which I have foundespecially desirable. A

' specific example of a synthetic resin which I energy-absorbing devicelill carried by the key 1 III (specifically by its rearwardly extendingbar |31) underneath the adjustable hammer screw I above described. Theretaining means of the device |50 may conveniently include an uprightcup Il! inset into the top of the bar |31. The cup |52 is filled with amass III oi' the material. The cup is centralized underneath the screw|48 so that the latter tends to be pushed against by the material uponkeydepression (i. e., rise of |31 and |50). To prevent undue penetrationof the material by the screw |49, sticking of the screw in the material,and for other reasons apparent immediately below, the material Il may inthis construction be covered by a very thin membrane |53 of soft rubber,which may be ccnsideri as completing the retaining means. The membrane|53,

have employed to great advantage is that furnished by BakeliteCorporation under the designation of "Synthetic Resin 621-193B.

This material has roughly the appearance of live rubber and, at roomtemperature, approximately the consistency of a candy gum dropY (fromwhich the ordinary outer surface has been removed). It isnon-hydroscopic. It has elasticity, in that upon the removal of adeforming force it tends to restore to its prior configuration; but thisrestoration is very slow compared.

to that of rubber. It will extremely gradually respond to a sustaineddeforming force: thus to the force of gravity a solid sphere of thismaterial will respond by flowing to a fiat surface in a container in thesource of about a month at room temperature. Its variation ofcharacteristics with temperature is such that if heated to about 350degrees F. it will ow with about the consistency of cool molasses: theriormal characteristics abovementioned will be restored upon coolingback to room temperature. Heating to appreciably more than 350 degreesF., however, causes a fundamental change in thermaterial, such that itwill not thereafter recover its normal characteristics.

I may mention a method of constructing the devices ISI which I havefound very convenient and satisfactory. A suilicient mass of theabsorptlve material, of irregular shape, has been placed in the uprightcup |52, and a hot iron has been applied to soften the material so thatit flows to a full level in the cup, forms a thin film on the top rim ofthe cup, and disposes of its excess. The cup has then been promptlyinverted and pressed downy against a sheet of the membrane rubber. Uponcooling the membrane rubber has been trimmed away from the periphery ofthe cup rim, leaving the membrane I 53A secured in place by the materialitself.

While I have disclosed the preferred membrane |53 as of rubber, I havepointed out that it should be very thin in order to limit the resiliencewhich it introduces into the device. Since only limited resilience orrestorative tendency is wanted, it is possible quite satisfactorily toemploy other Inaterial inherently less resilient, such for example assilk or other cloth-particularly when the material lil is itselfcharacterized by a restorative tendency, as is the synthetic resinabovementioned.

As key depression is begun the membrane |53 of the device |50 willalmostrat once be brought up into contact with the bottom of the hammerscrew itl. The diameter of screwis appreciably less thanthe internal cupdiameter, so

that there is an opportunity for the mass Ill of absorptive material tobe deformed, by reduction in height immediately below the screw andincrease in height therearound; at this time, however, the tendencytoward this deformation is only slight, since the mass and inertia ofthe hammer are small. As key depression is continued the hammer, itsscrew I now driven through the device |50, will be propelled toward thestring. Very slightly before lthe hammer head reaches contact with thestring, the key movement is stopped by impingement of bar |81 on theup-stop formed by the Ielt strip |62; the hammer may then be said to betripped, or freed from operative connection with the key. It willcontinue its movement for the short distance required for striking, andwill then rebound through the same short distance, bringing the bottomof the screw |49 into impingement against the now-raised device |50.This impingement, occurring with a velocity dependent on original keyvelocity, will cause a corresponding degree of deformation of thematerial IBI. The work done in this deformation absorbs a large part ofthe energy of the rebounding hammer; the further work done in thesubstantial recovery from that deformation, urged by the limitedreslliencies of the material ISI and of the membrane |53, absorbs afurther large part of that energy, and renders the recovery so slow asto impart only the feeblest of bouncing motion to the hammer. insumcientto carry it back to the string.

While the initial deformation of the material I5I, attendant on thebeginning of key depression, has been noted to be only slight. itnevertheless may be suillcient to provide a beneficial automatic eirect.This deformation will comprise a slight reduction of height of thecentral portion of the device |50 underneath the screw |49; and thisslight reduction will be the greater. the greater the key velocity.During the minute interval between hammer tripping and the completion ofrebound, there will of course be essentially no restoration of thisreduced height to normal. Accordingly, the greater the key velocity andthus the greater the kinetic energy of the hammer, the greater is thedistance through whlchit rebounds from the string and thus the greateris the distance through which a bounce would have to extend in order tocause the unwanted second striking. On the other hand with low keyvelocities, when the minimum tripping (and rebound) distance isdesirable, substantially no reduction ofheight or increase of distanceoccurs.

It will of course be understood that with this embodiment repetition isjust as perfectly available as inlthe earlier embodiment. And, thoughnot necessary. there may if desired be employed as an additionalrefinement the collapsible' spring system ll-ll illustrated anddescribed in connection with the earlier embodiment.

Suitable string dampers, or vibration-terminators, may readily beprovided in the embodiment of Figure 5. The damper for each string maybea respective felt pad ill, held atthe top ol' a respective substantiallyvertical arm |12 disposed in a transverse plane behind the strings. Theann |12 may be formed of dat. light metal strip; and it will preferablybe provided with iianges l 12o folded forwardly from the side edges ofits top portion, to embrace the rear portions of the sides ioi' the padIII.A The bottom of the arm |12 may be a point of pivoting for the am.

a suitable pivoting arrangement being described below; and at this pointthe material of the arm may be bent to extend forwardly, passing closelyalongside the respective string through the plane of the strings. in theform of an arm |13. The arm |13 may extend to have its forward extremitynormally slightly spaced above a rearward lug or projections I 31aformed from the lower rear portion of the respective bar Ill; and theforward portion oi' the arm |13 may be sumciently weighted. as by weightIlla, to impart to the arms |13 and |12 a bias (clockwise asillustrated) urging the damping pad ill against the respective string.Upon key depression, however, the lug Illa will be brought upwardly intoimpingement against the bottom of arm |13, and will rock arms lll and|12 (counterclockwise as illustrated) to carry the damping pad llirearwardly out oi' contact with the string.

For supporting the dampers a transverse damper rail may be provided inthe form of wooden or other members |18 secured transversely oi' theinstrument between the successive T-beams Iithe front surface of therail may be advantageously inclined upwardly and rearwardly. Thepivoting of each damper arm system III-HI to the rail may be carried outby a respective suitable cloth strip ill folded back on itself at thepoint of juncture of the two arms, one fold of the strip extendingupwardly along and being secured to the back oi' arm |12. and the otherfold of the strip extending upwardly along and being secured to theinclined front surface of the rail Ill. A stop for possible overshootingmovements ofthe dempers may be provided in the form of felt or likestrip III secured along the top portion of the front surface of therail.

To remove all the dampers at once from contact with the respectivestrings, there may be provided underneath the forward extremities ofarms Il! a transverse rail ill; this may for example he held at theforward extremities of suitable arms lll, whose rear extremities arepivoted to pivots such as lll to establish a generally vertical, shortarcuate path of movement for the rail llt. A pedal such as IIS. actingthrough rod III, may upon depression lift the rail I and so move all thedempers rearwardly.

Itistobeunderstoodthatwhileinllgures 'l-B I have shown an energyabsorbing device of one particular construction, a great number ofalternative constructions are available. Two auch constructions havebeen illustrated by the respective bumpers Il and Il in Figure 6.'Ih'ese are of course not limited. in their utility with a hammer, toassociation with the auxiliary or secondary mass (rod) li-there beingobvious their equivalence in operation to the devices lll, as well asthe availability for them of materials similartothe mass Ill andmembrane ill ofthe latter devices.

Another typical construction I have illustratedinPlgureS-bywlyofexamplaineonnection with a cylindrical. axially movedhammer such as In this construction there is secured in the open bottomof th'e hammer Il (for example. belowatransversediscllsecuredwlthinthehammer a little. way from the bottom) a lightooilspringllwhichextendsforadistanoedownwardly from the hammer proper.within and around thissprlngisagenerally cylindricalmass Il of semi-duidabsorptive material, such as the synthetic resin abovementlonedJ-inother words. the spring Il h imbedded in the mass Il. The

spring accordingly functions as a resilient retaining means forprecluding permanent deformation of the material 58, but is of courseweak enough' so that the reaction of the device as a whole ispredominately a viscous one. The device may be completed by a very thindisc 59 of rubber, silk or the like adhering to the bottom oi thematerial and precluding any sticking to the capstan or screw lll. l

While not in its broader aspects limited thereto. it will be understoodthat the actions constructed according to my invention are particularlyadvantageous when, as illustrated, the mass of the hammer is a smallpart of the total mass moved by the key. Then there is automaticallyinsured t'he absence of any feeling by the players lingers of therebound of the hammer. The small-mass hammer is otherwise desirable whenthe vibrators to be excited are relatively small and light; suchvibrators are the preferred ones in instruments operating bymechanica-electro-acoustic translation (such as the illustratedelectronic pianos), and for these instruments my invention thus has anespecial utility.

While I have shown and described my invention in terms of particularembodiments thereof, it will be understood that the details of theseembodiments may be varied within wide limits without departure from thetrue spirit or proper scope oi' the invention. That scope I undertake toexpress in the appended claims.

I claim:

1. In a musical instrument, an exciting action for a vibratorcomprising, in combination, a hammer movable to strike the vibrator;stop means against which the hammer rebounds after striking thevibrator; and means, carried by and movable relatively to the hammer,for suppressing bouncing of the hammer from said stop means back to thevibrator.

2. In a musical instrument, an exciting action for a vibratorcomprising, in combination, a hammer movable to strike the vibrator;stop means against which the hammer rebounds after striking thevibrator; and means, comprising a mass moved by and relatively to thehammer, for suppressing bouncins i' the hammer from said stop means backto the vibrator.

3. The combination according to claim 2, wherein there is comprisedmeans for causing a viscous resistance to the movement of said massrelative to the hammer.

4. In a musical instrument, an exciting action for a vibratorcomprising, in combination, a hammer movable to strike the vibrator:stop means against which the hammer rebounds after striking thevibrator; and means, comprising an efiectively fluid mass characterizedby a high effective viscosity and subjected to internal movement by thehammer, for suppressing bouncing of the hammer from said stop means backto the vibrator.

5. In a musical instrumenta, an exciting action for a vibratorcomprising. in combination, a hammer movable to strike the vibrator;stop means against which the hammer rebounds after striking thevibrator: and visco-elastic means characterized by a predominatelyviscous reaction for suppressing bouncing of the hammer from said stopmeans back to the vibrator.

6. In a musical instrument, a key-operatedexciting action for a vibratorcomprising, in combination, a hammer movable to strike the vibrator;key-moved means for impeiling the hammer toward the vibrator and actingas a stop for the rebound thereof; and means, carried by and movablerelatively to the hammer, for suppressing bouncing of the hammer fromsaid keymoved means back to the vibrator.

7. In a musical instrument, a key-operated exciting action for avibrator comprising, in combination, a hammer movable to strike thevibrator; key-moved means for impelling the hammer toward the vibratorand acting as a stop for therebound thereof; and means, comprising aneffectively fluid mass characterized by a high effective viscosity andsubjected to internal movement by the hammer, for suppressing bouncingof the hammer from said key-moved means back to the vibrator.

8. In a musical instrument, an exciting action for a vibratorcomprising, in combination, a hammer movable to strike the vibrator;stop means against which the hammer rebounds after striking thevibrator; and means, loosely carried by the hammer, for effecting abounceopposing impact on said hammer at the conclusion of hammerrebound.

9. In a musical instrument, an exciting action for a vibratorcomprising, in combination, a hammer movable to strike the vibrator;stop means against which the hammer rebounds after striking thevibrator; and means, loosely carried by the hammer, for effecting arebound-opposing impact on said hammer at the beginning of hammerrebound and a bounce-opposing impact thereon at the conclusion of saidrebound.

10. In a musical instrument, a vibrator-exciting action without anescapement comprising, in combination, a hammer movable to strike thevibrator and to rebound therefrom; and means, loosely carried by thehammer, for effecting an opposing impact on the hammer upon its reboundfrom the vibrator.

11. In a musical instrument, a vibrator-exciting action without anescapement comprising, in combination, a hammer movable to strike thevibrator; a mass carried by the hammer and subjected to movementrelative thereto when the hammer strikes the vibrator; and viscousdamping means associated with said mass and eti'ective upon saidrelative movement.

12. In a musical instrument, an exciting action for a vibratorcomprising, in combination, a hammer movable to strike the vibrator;stop means against which the hammer rebounds after striking thevibrator: a mass carried by the hammer and subjected to movementsrelative thereto when the hammer strikes the vibrator and when thehammer strikes said stop means; and viscous damping means associatedwith said mass and eil'ective upon said relative movements.

13. In a musical instrument, a vibrator-exciting action without anescapement comprising, in combination, a hammer movable to strike thevibrator and to rebound therefrom; means, carried by the hammer, foreffecting an opposing impact on the hammer upon its rebound; andefiectively viscous means subjected to deformation by the hammer uponits rebound for absorbing energy from the rebounding hammer.

ing action without an escapement comprising. in combination, a hammermovable to strike the vibrator and to rebound therefrom; effectivelyviscous means subjected to defamation by the hammer for absorbing energyfrom the rebounding hammer; and resilient means associated with saidlast-mentioned means tor restoring the same to a normal configuration.

16. In a musical instrument, a vibrator-exciting action without anescapement comprising, in combination, a hammer movable to strike thevibrator and to rebound therefrom: effectively viscous means subjectedto deformation by the hammer for absorbing energy from the reboundinghammer; and resilient means within said last-mentioned means forrestoring the same to a normal consuration.

17. In a musical instrument, a key-operated exciting action for avibrator comprising, in combination, a hammer movable to strike thevibrator; key-moved means for impelling the hammer toward the vibratorand acting as a stop for the rebound thereof; and Visco-elastic meanscharacterized by a predominately viscous reaction interposed betweensaid last-mentioned means and the hammer.

18. In a musical' instrument. a vibrator-exciting action operated by alimitedly movable key comprising, in combination, a hammer moved by thekey to a relatively small spacing from the vibrator and thereafter movedby its own momentum to strike the vibrator and to rebound therefromthrough said spacing; and movementtransmitting means, interposed betweenthe hammer and the key, yieldable in accordance with the velocity of keymovement and characterized by slow recovery, whereby said spacing iscaused to vary with the velocity of key movement.

i9. In a musical instrument having a vibratorexciting action: thecombination of a depressible key included in and operating said action;and collapsible spring means rendered eil'ectlve by said key in itsdownstroke, for first building up and then releasing an impedance tosaid downstroke. 4

BENJAMIN F. MIESSNER.

